It’s too long since I last posted on this blog. Two months!

Somehow, the individual tiny steps don’t seem to merit a mention but, taken together, there’s a couple of strides’ worth of stuff to report.

The hog:

Having steamed the aft end of the hog, I took the hog to the loft floor, and marked it with all the reference lines I could think of: the station lines, where each mould will sit; the position of the centreboard slot; and the position of the timbers (ribs) that will be steamed in place once planking is completed.

It was now time to glue and screw the hog to the keel. With a series of blocks screwed to the strongback, the keel could be held perfectly straight; and some smaller scraps of wood were nailed onto the blocks so that the hog would be perfectly centred on the keel when butted up to them. Such careful preparation is essential because you cannot see pencil lines to judge accurate positioning when the glue is squeezing out. As our son James was told at Dartmouth Royal Navy College, ‘Prior preparation prevents piss poor performance!’

A dry run, with the stem clamped in position, to ensure the hog’s position for and aft is correct. You can never have too many clamps!!

Sylvia and I did the glue up.

Once the glue had gone off, the blocks were removed and set up on the centreline of the strongback. With plywood ‘cheeks’ screwed in place, the keel and hog were firmly in place, and counterbored silicon-bronze screw fixings were fitted.

The keel is held very firmly, and the plywood ‘cheeks can be unscrewed temporarily to allow access when fitting the garboard (first) plank.
The counterbored holes for the screw fixings have been plugged.

Transom knee:

The transom sits on the keel, and is held in place by the transom knee, which serves as a bracket. There are a number of ways to make this important knee: grown curved timber, lapped or bridle jointed pieces of wood or, as I chose, a laminated knee. The key is to have the grain matching or supporting the inner curve of the knee to give the necessary strength to this member of the boat’s centreline/backbone.

Using a template made out of Mylar, taken off a drawing added to the loft floor, a jig is made, bolted firmly to an old tabletop.
Thin (2-3mm) strips of oak are bent around this jig with a carefully shaped inner ‘chock’ of wood.
Using Resorcinol, the laminations are glued up with the inner ‘chock.’ Lots of clamps required again!!!!
After cleaning up, and thicknessing, the …
… resulting knee is marked out and cut to the shape of the template.

Holes were then drilled in the knee (and then through the deadwood and keel), and the knee was glued onto the hog with Semparoc 60 polyurethane glue. Having made some more 5mm copper nails, the knee was then nailed and roved, with Sylvia’s assistance.

Stem fixing:

With the hog glued and screwed, it was also time to fix the stem to the keel.

With the kind help of my friend, Matt, a plumb bob ensured that the stem was vertical, and …
… the stem was glued in place with Semaproc 60.
With the whole structure moved to the workshop, the holes were carefully drilled through the keel. Happily, they came out nicely central/very close.

Sylvia and I then roved the copper nails that I had made, finishing the stem fixing.

Finally, the transom:

I mentioned the transom in my last post. This has been made from three pieces of Khaya mahogany, jointed together with 3mm marine plywood splines. These splines bridge the butt-jointed planks, running in grooves that I routed with a power router. Despite my apprehension that the router would pull off line, this step went very well, and a quick swipe with a Record plough plane finished the job nicely.

Opposing clamps, and a central crossbeam clamped in place, ensures that the jointed piece comes out flat.
Plywood is made using laminations with the grain of each veneer at right angles to the adjoining sheets. This ensures that they cannot split down their length, making the joint very strong if flexed. A tongue and groove joint would be liable to failure, as all the grain is parallel to the joint.

With the epoxy glue cleaned up, it was time to make my transom Mylar template from the lines of the transom expansion on my loft floor. (The transom expansion is the process of stretching the ‘height’ dimension of the transom, in order to account for the fact that it is raked, not plumb/vertical.)

The two sets of lines represent the shape of the inner and outer faces of the transom, once the width of the plank is subtracted. The inner face of the transom is larger than the outer face, because the planks are curving inwards towards the stern of the boat (just as with the stem.)
Cutting the template to the shape of each face in turn, allowed accurate transfer of the lines to the wood. Because the transom is raked (angled), the waterlines are higher on the aft template than on the forward/inner face – hence the parallel waterlines seen here.

Once the transom had been cut to shape, it was put in place, with a plywood jig positioned to hold the keel in place.

A saw-kerf cut technique is used to get the transom-keel joint really tight, using this Japanese saw which has a very thin blade.
With the saw removed, the transom drops 0.5mm to a snug fit.

With the transom fitting nicely, I turned my attention to carving the boat’s name.

I am pleased with this result. I will now have to get the moulds beveled and set up, and the transom glued with its fixings fitted.

An aside:

While enjoying a break away in Bradford on Avon, I managed to finish a little project for my woodturning mentor and friend. I am delighted to hear from Richard that this sign has drawn in the punters to his recent craft stall events. Perhaps I should have asked for a percentage of the resulting increased sales!! (Just joking, Richard.)

5 thoughts on “Dinghy Developments.

  1. Wonderful update and superb work. Well done indeed. Your eye for detail is excellent, I cant wait to see it!

    1. Thanks Matthew, I’ll let you know when it’s all set up with moulds in place – it’ll look like a boat then!

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